The present invention relates to a scroll-type fluid machine suitable in use for an air compressor, a vacuum pump and an expansion machine.
A known scroll-type fluid machine is disclosed in Japanese Patent No. 2,971,652.
The fluid machine comprises an orbiting scroll that is connected to a drive shaft rotated by an AC electric motor to be able to revolve and has a spiral orbiting wrap on one side surface, a stationary scroll that faces the orbiting scroll and has a stationary wrap to form a compression chamber between the stationary and orbiting wraps, and tip seals that seals the compression chamber at the ends of the stationary wraps of the stationary scroll to be in sliding contact with the surface of the orbiting scroll.
For example, if the scroll compressor set by frequency of 50 Hz for East Japan is used in West Japan, the tip seal is made to be shorter not to seal the winding finish of the stationary wrap. Therefore, even if the number of rotation of the AC electric motor becomes higher by the frequency of 60 Hz for West Japan, it prevents the scroll-type fluid machine not to be subject to overload operation. That is, the length of the tip seal can be changed depending on the frequency of AC voltage applied to the AC electric motor.
However, in the known scroll-type fluid machine as above, it is necessary to change the length of the tip seal depending on the condition of use, and thus, various types of tip seals having different lengths have to be provided. Thus, it is impossible to use the same type of tip seals, thereby increasing cost. To replace the tip seal, it is necessary to remove other parts to involve troublesome replacement.
In view of the disadvantages as above, it is an object of the present invention to provide a scroll-type fluid machine that need not replacement of parts even if condition in use is different, to prevent overload.